CVE-2018-25254: NICO-FTP Buffer Overflow Vulnerability

CVE-2018-25254 Overview

CVE-2018-25254 is a critical structured exception handler (SEH) buffer overflow vulnerability in NICO-FTP 3.0.1.19 that allows remote attackers to execute arbitrary code. By sending crafted FTP commands, attackers can connect to the FTP service and send oversized data in response handlers to overwrite SEH pointers and redirect execution to injected shellcode.

Critical Impact

Remote attackers can achieve complete system compromise through arbitrary code execution by exploiting the SEH buffer overflow in NICO-FTP's command handling functionality.

Affected Products

• NICO-FTP version 3.0.1.19

Discovery Timeline

• 2026-04-04 - CVE-2018-25254 published to NVD
• 2026-04-07 - Last updated in NVD database

Technical Details for CVE-2018-25254

Vulnerability Analysis

This vulnerability is classified under CWE-787 (Out-of-Bounds Write), which occurs when the software writes data past the end of the intended buffer. In the case of NICO-FTP 3.0.1.19, the application fails to properly validate the length of data received from FTP commands before processing them. This allows an attacker to craft malicious FTP responses that overflow the buffer and overwrite critical memory structures, specifically the Structured Exception Handler (SEH) chain.

When the SEH is overwritten with attacker-controlled values, the application's normal exception handling flow is hijacked. Upon triggering an exception, instead of executing legitimate error handling routines, the application jumps to attacker-specified code, enabling full remote code execution.

Root Cause

The root cause of this vulnerability lies in improper bounds checking within the FTP command response handling routines. The application allocates a fixed-size buffer for processing FTP server responses but does not verify that incoming data fits within this allocated space. When oversized data is received, it overwrites adjacent memory regions, including the SEH pointer stored on the stack. This is a classic example of a stack-based buffer overflow that specifically targets Windows SEH structures for exploitation.

Attack Vector

The attack is network-based and requires no authentication or user interaction. An attacker can establish a connection to the vulnerable NICO-FTP client by setting up a malicious FTP server or by intercepting and modifying FTP traffic. When the victim connects to the attacker-controlled server, crafted FTP responses containing oversized payloads are sent to trigger the overflow. The payload includes carefully positioned values that overwrite the SEH pointer with the address of attacker-controlled shellcode, which executes when an exception is triggered.

The exploitation technique typically involves:

1. Sending an oversized response that fills the vulnerable buffer
2. Overwriting the SEH pointer with a "pop-pop-ret" gadget address
3. Placing shellcode after the SEH overwrite
4. Triggering an exception to redirect execution flow

For detailed technical analysis and proof-of-concept code, see the Exploit-DB #45442 entry and the VulnCheck Advisory.

Detection Methods for CVE-2018-25254

Indicators of Compromise

• Unusual crash behavior or unexpected termination of NICO-FTP.exe process
• Presence of network connections to suspicious or unknown FTP servers
• Anomalous FTP response traffic containing unusually large payloads
• Evidence of shellcode execution or suspicious child processes spawned from NICO-FTP

Detection Strategies

• Monitor network traffic for FTP responses exceeding normal size thresholds
• Deploy endpoint detection rules to identify SEH overwrite patterns in memory
• Use intrusion detection systems (IDS) to flag malformed FTP protocol communications
• Implement application whitelisting to prevent unauthorized code execution from FTP client processes

Monitoring Recommendations

• Enable verbose logging on FTP client applications and review for anomalous activity
• Monitor process behavior for NICO-FTP, specifically tracking child process creation
• Implement network segmentation to limit exposure of vulnerable FTP clients
• Deploy SentinelOne agents on endpoints running NICO-FTP to leverage behavioral AI detection

How to Mitigate CVE-2018-25254

Immediate Actions Required

• Discontinue use of NICO-FTP version 3.0.1.19 immediately
• Migrate to an alternative, actively maintained FTP client software
• Implement network-level filtering to block suspicious FTP traffic
• Deploy endpoint protection solutions capable of detecting memory corruption attacks

Patch Information

No vendor patch information is available for this vulnerability. NICO-FTP appears to be a legacy application that may no longer receive security updates. Organizations should consider this software end-of-life and migrate to supported alternatives. Additional information can be found in the VulnCheck Advisory.

Workarounds

• Remove or uninstall NICO-FTP 3.0.1.19 from all systems
• Use alternative FTP clients such as FileZilla, WinSCP, or other actively maintained software
• If removal is not immediately possible, restrict network access to only trusted FTP servers
• Enable Data Execution Prevention (DEP) and Address Space Layout Randomization (ASLR) at the OS level to make exploitation more difficult

# Windows: Verify DEP is enabled for all programs
bcdedit /set nx AlwaysOn

# Check for NICO-FTP installations across the network
wmic product where "name like '%NICO%FTP%'" get name,version